Uncontrolled Memory Allocation in Netty - CVE-2026-45416
Published: June 8, 2026
Vulnerability identifier: #VU133450
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-45416
CWE-ID: CWE-789
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Netty project
Affected software:
Netty
Netty
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled memory allocation in SslClientHelloHandler.decode() when processing a TLS ClientHello that does not fit in the first record. A remote attacker can send a specially crafted ClientHello with a large handshake length to cause a denial of service.
The issue is exposed by the commonly used SniHandler and AbstractSniHandler constructors because they disable the client hello length guard and do not schedule a handshake timeout.
How to mitigate CVE-2026-45416
Install security update from vendor's website.